Advancing Optical Precision: Metasurface Metrology With Phasics' Cutting-Edge Technology

Metasurfaces are composed of tiny elements called building blocks or meta-atoms, which are used to control light where two different materials meet. These surfaces can be divided into two types: local metasurfaces, where each element works independently, and nonlocal metasurfaces, where elements are connected and work together. Metasurfaces manipulate the way light travels, allowing them to direct light in specific directions, focus it like lenses, or project certain light patterns, such as with holograms. They achieve this through several methods, including guiding light through small structures, using structures that resonate to affect light, and changing the light’s polarization with specially oriented elements. These techniques allow metasurfaces to perform complex optical tasks in compact and efficient ways, making them valuable for advanced technology applications while remaining simple to integrate into devices.

Despite their significant advantages, metasurfaces pose unique challenges in metrology—the science of measurement. The nanoscale features of metasurfaces demand high-resolution, high-precision measurement techniques to accurately assess their optical properties and ensure performance consistency across production batches.

1. Amplitude Measurements: Quantifying light transmission/reflection efficiency is essential for evaluating metasurface performance. However, nanoscale structural variations introduce localized losses, leading to inconsistent efficiency across devices. Traditional intensity-based methods struggle to resolve subtle fluctuations critical for applications like metalenses and metadeflectors.
2. Phase Reconstruction
   Metasurfaces rely on precise phase modulation to shape wavefronts. Direct phase measurement is inherently impossible with photodetectors, which only record intensity. Current solutions, such as interferometry and computational phase retrieval, face trade-offs between accuracy, speed, and complexity, especially for large-area or high-resolution metasurfaces.
3. Polarization characterization:
   Dynamic polarization control is central to metasurfaces in imaging, sensing, and communication systems. However, conventional polarization analyzers lack the spatial resolution and compatibility required to map polarization states at the subwavelength scale, limiting their utility in miniaturized metasurface-integrated devices.

Industrializing metasurfaces involves scaling up production without compromising the intricate nanostructures that define their functionality. Achieving uniformity and high yields while maintaining cost-effectiveness and meeting stringent manufacturing standards represents a significant industrial challenge.

Phasics’ QWLSI Technology: An advanced Solution for Metasurface Metrology
To address these challenges, Phasics leverages its patented Quadriwave Lateral Shearing Interferometry (QWLSI) technology. QWLSI combines high spatial resolution, achromatic operation, and compact design. The technique employs a diffractive grating to split incident light into four coherent waves, generating interferograms that encode both phase gradients and intensity distributions. Phasics’ SID4 series wavefront sensor, powered by QWLSI technology, delivers nanometric phase sensitivity and real-time data acquisition. Key applications include:

• High Resolution and Sensitivity: Essential for inspecting nanostructures and ensuring precise measurements.
• Optical function validation: Assessing metalens focusing efficiency and aberration control.
• Imaging quality analysis: Capable of assessing wavefront, imaging quality (PSF & MTF in one shot), and metasurface structure.
• Robustness and Compatibility: Integrates easily with standard microscopes, enhancing reliability and reproducibility.

As compact, efficient, and highly functional optical devices, metasurfaces push innovation across various industries. The integration of Phasics' metrology solutions into the production and testing phases ensures that these advanced materials meet the rigorous demands of modern optical applications.